In order to prevent, for example, rupture of a battery case when the internal pressure of the battery rises due to the generation of heat by, for example, an internal short circuit, a known battery having a gas discharge port in a sealing body or in a bottom portion of the battery case is provided (see, for example, Patent Literature 1). According to Patent Literature 1, in order to stably discharge gas during thermal runaway, an electrode-body-side surface of an insulating plate that is disposed between the electrode body and the gas discharge port is provided with a protruding portion, and a particular cyclic ether compound is added to a nonaqueous electrolyte.